Co-occurrence of selenium and toxic elements and health risk assessment in commercial selenium-enriched rice from China

Selenium (Se) is an indispensable micronutrient critical for human health, with rice being a primary dietary source. However, Se-enriched rice may co-accumulate toxic elements, posing dual challenges of nutritional supplementation and toxicological risks. This study systematically evaluated 54 commercially available Se-enriched rice samples from 14 Chinese provinces through quantification of Se, arsenic (As), and cadmium (Cd) concentrations, coupled with bioaccessibility assessment and health risks. The results demonstrated that while arithmetic mean As (0.11 mg/kg) and Cd (0.08 mg/kg) concentrations remained below national safety thresholds (0.2 mg/kg for As; 0.2 mg/kg for Cd), only 46.3% of samples satisfied Chinese Se-enriched cereal standard (≥ 0.04 mg/kg). The arithmetic mean Se concentration was 0.13 ± 0.14 mg/kg, with an arithmetic mean bioaccessibility of 14.6% ± 8.7%, suggesting significant nutritional bioavailability constraints. Estimated daily intakes (EDIs) and hazard quotients (HQs) for As and Cd were acceptable, though children exhibited the highest EDIs for toxic elements and the lowest Se intake, indicating a potential vulnerability. These findings highlight the dual nature of Se-enriched rice as both a functional food and a potential exposure pathway for toxic elements, emphasizing the need for careful monitoring and targeted dietary guidance.